MXR
MXR was a popular electric guitar effects manufacturer which began in the 1970's in New York
The original pedals manufactured were-
MXR Dyna Comp (Compressor), MXR Blue Box (Analog Distortion and Octave), MXR Distortion+, MXR Envelope Filter, MXR Micro Amp, MXR Micro Chorus, MXR Stereo Chorus, MXR Phase 90, MXR Phase 100
Jim Dunlop (the company famous for the Cry Baby Wah-Wah) currentlly manufacture reissues of some of the classic MXR effects pedals. They have even created their own new models in additon to the original line up.